The present invention relates generally to a conveyor, and more particularly to a drag-chain conveyor. Still more particularly, the present invention relates to a drag-chain conveyor provided with an arrangement for gas-tightly and dust-tightly sealing the outlet openings of the conveyor passage.
Drag-chain conveyors are widely used in connection with batteries of industrial furnaces, such as coking ovens and the like, to supply the coal or coke in cold or pre-heated condition to the respective oven chambers, into which they are then admitted as a charge. Such ovens, when arranged in form of a battery, are located side-by-side so that the battery is elongated. The drag-chain conveyor is usually mounted approximately 5 or 6 meters above the upper ceiling of the battery of ovens, and above each oven chamber the bottom wall of the passage or duct in which the dragchain of the conveyor advances, is provided with an opening from which a usually funnel-shaped chute extends downwardly. The chute can be closed with a slidable closure plate and, when the latter is opened, coal or coke which is advanced along the passage by the drag-chain of the conveyor, can fall out of the opening and through the chute into a charging larry or the like which is positioned beneath the chute and which usually travels on rails thart are mounted on the upper ceiling of the battery of furnace chambers. This larry or other equivalent device then transports the charge of coal or coke to the charging hole of the respective oven chamber and admits the coal or coke into this charging hole.
These prior-art arrangements have a significant disadvantage. They operate well when coal or coke is to be admitted into that discharge opening and chute that is associated with the oven chamber located at the inlet end of the drag-chain conveyor, that is at the end where the conveyor is being fed with coal or coke which it then advances by the drag action of its chain links. If, however, coal or coke is to be introduced into the second or any following opening, then all openings preceding the one which it is intended to fill with coal or coke, will similarly receive a charge of coal or coke. This means that the funnel-shaped chutes of each of these openings become filled with the coal or coke since these chutes are normally closed by their respectively associated closure plate which is of course opened only when the coal or coke is to be discharged from the chute into a larry or similar device located beneath the latter. In the region where these chutes are unintentionally filled with coal or coke, the conveying action of the drag-chain conveyor is significantly impaired because the coal being advanced by the conveyor must now slide over the coal which fills the respective chute. The increased friction requires increased force to be able to advance the drag chain of the conveyor. This, however, has the disadvantage that the links of the drag chain are subjected to substantially increased wear. If the coal or coke is preheated before it is fed to the conveyor, then those quantities of coal which accumulate in the discharge chutes from which they are not immediately to be discharged, will cool and tend to cake together. When this takes place, a later opening of the closure plate will not result in discharging of the contents of the respective chute, because the contents have caked together into a solid mass.
Moreover, the prior-art conveyors of this type, which have their slidable closure plates located within the chute so that the latter can fill up above the respective closure plate, do not provide for a dust-tight and gastight sealing of the chute, which is disadvantageous in terms of contamination of the ambient atmosphere.